Diabetic retinopathy is a major cause of blindness in the United States. While earlier detection and major advances in laser therapies have made significant impact on this chronic complication of diabetes, the number of diabetic patients suffering from diabetic retinopathy continues to increase. The Diabetes Control and Complication Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) have both documented the benefit of tight blood glucose control on diabetic retinopathy and peripheral neuropathy. However, it is clear that tight blood glucose control was insufficient in 25% or more of the study participants to protect them from the onset or progression of diabetic retinopathy or neuropathy. It can be inferred that the number of patients who continued with tight control and nevertheless suffered from retinopathy and neuropathy would increase as time progressed. Indeed, during the first 1 to 1.5 years of studies designed to determine if tight blood glucose control would lessen diabetic complications, diabetic retinopathy actually increased dramatically in the tightly controlled patients. Other physicians have noted this increase in diabetic retinopathy in patients undergoing an acute and significant improvement in their blood glucose control. In the past, such worsening of diabetic retinopathy was attributed to decreased blood circulation in the retina and a consequent diminution in oxygen delivery to that tissue. However, such an explanation seemed less than credible in view of the short time course (1–1.5 years) and especially to the temporal relationship to the dramatic improvement in blood glucose control. This dichotomy suggested that the sudden worsening/appearance of diabetic retinopathy and other indications of neuropathy were linked to the fall in fasting, postprandial, and interprandial blood glucose levels.
What is needed is a system that increases retinal and neural glucose oxidation by enhancing pyruvate dehydrogenase activity and therefore treat retinopathy and central nervous system disorders in both diabetic and non-diabetic patients.